Feature: allow comparing post edits against any previous revision (not only the immediately prior one)

[Moin]

I think this was requested before in

How can I compare arbitrary revisions of a post?

Revision history is useful. It’s nice to be able to see the diff between any 2 adjacent revisions (revs 3 and 4, or revs 8 and 9), but this is really insufficient when a post has been changed substantially over time, or if someone makes a bunch of small changes saving each as they go, especially if they multiply revise those changes. I very much need to be able to see the diff between, for instance, rev 3 (which I produced) and rev 9 (which is the current, having been changed by multiple edit…